Intensity Pro Playback

Greeting All I'm having Trouble with my HDMI output card its a Intensity Pro and I have it running into a 42" lcd for clients to view. Now I've had no problems up until now. For some reason it will show the video in RT when i scrub though the time line and when i play a clip in the Viewer window but when i just play the video through the normal TImeline it wont play it back in RT just stays on the single frame. I have it set to all frames, now the only thing different is Im running it though a External HD rather than my internal raid is this the problem? if so why will it preview the clips in the Viewer window in RT but nothing else. Thanks for the help.

Just transferred all the Data to my RAID Still wont playback in Real Time. What the hell? it will scrub in Real time and the clips in the viewer window will play back in Real time why wont the timeline play back in Real time?